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The Indomitable Magnetic Resonance Imaging System is indicated for use in producing images of multiple planes in the head and body. These images correspond to the distribution of hydrogen nuclei exhibiting nuclear magnetic resonance (NMR) and depend for their contrast upon NMR parameters [hydrogen nuclei concentration and flow velocity, T1 (spinlattice relaxation time) and T2 (spin-spin relaxation time)]. As a result of the acquisition and processing of the NMR data, these images display the internal structure of the head and body, and when interpreted by a trained physician, can vield diagnostically useful information.

FONAR Corporation has modified the existing control limits for the Indomitable scanner gradient subsystem to allow the maximum gradient current to increase by 50 percent, with a corresponding increase in the maximum slew rate for the gradient waveforms. All other subsystems remain essentially unchanged from their previously approved (K002490) state. This modified gradient subsystem follows the same basic design principles as our previously approved gradient systems. It functions on the same basic operating and physical principles as the predicate device, the Indomitable gradient system (K002490). It is constructed with the same manufacturing materials, and is fabricated in the same fashion to the previously approved gradients. The primary differences of this modification to the gradient subsystem are the software limits for maximum gradient current value and the increased slew rate that accompanies the changed current value. It is, in summary, a significant equivalent of FONAR's currently approved predicate device.

The FONAR 360° Magnetic Resonance Imaging System is indicated for use in producing images of multiple planes in the head and body. These images correspond to the distribution of hydrogen nuclei exhibiting nuclear magnetic resonance (NMR) and depend for their contrast upon NMR parameters [hydrogen nuclei concentration and flow velocity, T1 (spinlattice relaxation time) and T2 (spin-spin relaxation time)]. As a result of the acquisition and processing of the NMR data, these images display the internal structure of the head and body, and when interpreted by a trained physician, can yield diagnostically useful information.

The FONAR 360° magnet follows the same basic design, operating and physical principles, and construction methods and materials of the predicate magnets. The field strength of this magnet is 6000 gauss (0.6T). This magnet configuration is essentially a combination of basic structural elements of Fonar's previously approved magnets. The two pole assemblies of the vertical-field iron-core electromagnet are separated and supported by steel supports that form the "walls", "ceiling" and "floor" of the room-sized magnet. This provides an unimpeded 360° access to the magnet's imaging gap. The electromagnet coil elements are windings of multiple turns of epoxy-insulated copper installed around the poles of the magnet frame, connected to a regulated power source, and chilled via the closed loop chiller system. During operation, the poles of the magnet establish a vertical magnet field with a limited fringe field. The magnetic field is created by passing a regulated DC current through the coil windings surrounding the magnet poles. The field strength is proportional to the amount of current in the coils. In this magnet the current supplied will result in a magnetic field of 6000 gauss, ± 5% (0.6T ± 5%), operating at frequencies between 24.27 and 26.92 MHz. This magnet functions with all imaging sequences available in the current software releases. All other non-magnet related equipment and procedures used are as previously reviewed by the FDA in PMA 830076, its supplements, and the 510(k) submissions K910839 and K951681. The transmitter coil for the Fonar 360° is modified from the coil used in the Quad 12000 magnet to accommodate the openness of the gap and the removal of the vertical posts of the Quad magnet construction. The resulting transmitter coil is configured as a quadrature coil instead of the linear coil used in the Quad. While the construction methods are different, the resulting field after application of the RF power produces the same level of excitation as the previously approved coils, and results in images that are equivalent to those produced by the predicate devices.